In the field of wireless telecommunications, it is known to equip communications devices with location determination hardware and software. Such hardware and software can either be integrated into the communications devices or provided as plug-in modules. With the decrease in cost of location determination hardware, provision of such hardware with communications devices is becoming more commonplace.
As communications devices comprising location determination hardware, for example Global Positioning System (GPS) receivers, become more commonplace, so-called location-based services and applications are becoming increasingly popular. In this respect, it can be desirable for a third party to “poll” a communications device, for example a cellular communications handset, with a location query. For example, a parent may wish to know a location of a child at a particular instant in time, an individual may want to know a location of a work colleague, or an individual may want to locate a friend.
However, at some locations, for example at a soccer match or a rock concert, a location query cannot be received or a response to the location query cannot be provided owing to a lack of network capacity. At other locations, for example in a hospital or in an aeroplane, use of wireless communications devices is simply not permitted. Likewise, at yet other locations for example a cinema or theatre, use of the wireless communications devices is undesirable. Where a response is not provided to the location query, the uncertainty accompanying the lack of response frustrates a decision as to a course of action to take based upon the location of a communications device being targeted.
In some circumstances, wireless communications devices are contactable, but ignored by their users owing to location or circumstances of the user. In this respect, some wireless communications devices have a vibrate alert setting or “silent” setting that can be selected by the user as an alternative to audible alerts provided by ring tones. In relation to Short Messaging Service (SMS) messages, or “texts”, some communications devices do not vibrate to signify receipt of an SMS message. When this happens, knowing the circumstances of the user and/or providing an emergency alert to the user in emergency situations is useful.
Whilst Home Location Registers (HLRs) and Visitor Location Registers (VLRs) used in cellular communication systems, such as systems using Global Systems for Mobile communications (GSM) network protocols and Terrestrial Trunked Radio (TETRA) network protocols, may be aware of current or last known locations of wireless communications devices, such information is operationally and commercially sensitive. Release of this information to members of the public by network operators is therefore unlikely. Additionally, no Application Programming Interface (API) is available for use by a software application to access the location information from the HLR and/or VLR. Further, the level of detail provided by the HLR and/or VLR is limited to cell identities and so is of limited value, particularly as no information is provided as to when an unreachable wireless communications device might become reachable again. Also, it is highly likely that users of wireless communications devices want to limit dissemination of personal location information on privacy and/or security grounds.